1. Field of the Invention
This invention relates to the suppression or prevention of arcing between electrical connectors as the connectors are mated and unmated so as to minimize potential damage to mating contacts due to arcing. This invention also relates to mating electrical connectors which are mechanically unstable in an arc susceptible position so that spring or biasing forces are generated that will tend to physically move the mating connectors away from a partially mated, arc susceptible position. This invention is also related to the generation of inertial forces due to the deformation of connectors housing members during mating in such a way that the inertial forces will tend to move the connectors away from a partially mated, arc susceptible position.
2. Description of the Prior Art
Currently there appears to be no inexpensive and reliable technology to prevent arcing at relatively low voltages of approximately 50 volts or less in electrical connectors. A 42-volt electrical architecture will soon be adopted for automotive electrical systems, and arcing is a problem that must be addressed. Any solution to this problem should be fully automatic and allow safe hot mate and unmate without damage to an operator or appreciable damage to the connector or the connector terminals.
U.S. Pat. No. 6,217,356 discloses one approach to prevent damage to mating terminals due to arcing. A secondary contact surface is provided at the tip of a terminal that mates with a pin terminal. Arcing damage is limited to the secondary contact surface and the portion of the pin that first comes close to the secondary or sacrificial contact surface. The main contact regions on both mating terminals are spaced from the sacrificial areas. This type of solution adds length and size to the terminals and to the electrical connectors in which they would be used. Therefore it has disadvantages when applied to an application in which a large number of terminals are positioned in a single connector and in which space and mating force are serious considerations.
If electrical connectors are properly mated and not mated and unmated under load, arcing is not a problem. A great deal of effort has been expended to provide to insure that automotive electrical connectors are properly mated. Mechanical assist devices, such as levers, are commonly employed. Guide plates eliminate stubbing during mating to prevent damage to the terminals. Guide plates also protect an operator from shocks. Connector position assurance devices that can only be manually actuated if the connectors are fully mated are also employed to insure that electrical connectors have been fully mated.
Another approach that has been employed is the use of inertial locks which will either snap connectors into a fully mated configuration or will force the connectors apart. U.S. Pat. No. 4,010,998 discloses the use of an inertia lock in which, once a sufficient mating force has been applied, mating cannot be stopped until the connectors are locked and the connector terminals are fully engaged. If an insufficient manual force is applied, the inertia lock will cause the connectors to xe2x80x9cself rejectxe2x80x9d. The inertial lock mechanism shown in U.S. Pat. No. 4,010,998 includes a latch arm on one connector that is deflected outward over a triangular locking ramp. The maximum mating force of the inertial lock mechanism is greater than the overall engagement force of the terminals so that the mating force tending to latch the connectors in place will be greater than the terminal engagement force. In other words, the maximum connector mating force exceeds the overall terminal engagement force. In many applications, such as automotive connector assemblies, the mating force is already too great and mechanical assist means, such as levers or bolts must be employed. However, these inertial locks are not typically used in conjunction with mechanical assist levers and guide plates and they are not used to prevent the connectors from occupying an intermediate, partially mated configuration in which mating terminals are in close proximity and susceptible to arcing.
The introduction of 42 volt electrical systems in automobiles and motor vehicles causes some concern that electrical terminals may be subject to arcing as electrical connectors are mated or unmated under load. Arcing has not been a significant problem for standard 14 volt electrical systems, because 14 volts is below the minimum arc voltage for most contact materials. A stable arc typically cannot exist below 15 volts. However, the power demands of vehicles are increasing to a point where the current 14 volt system is no longer adequate. All current terminals will arc when mated and unmated under load at 42 volts. All contact metals can sustain a stable arc above 20 volts. It is hoped, however, that the new 42 volt electrical systems can employ electrical connectors and terminals that do not differ significantly from those used in standard 14 volt systems. Although electrical connectors are not typically mated and unmated under load, even infrequent occurrences can result in problems. Most automotive electrical connectors include connector position assurance devices that are supposed to insure that connectors are fully mated and not left in a partially mated configuration. However, they require manual operation and will only achieve their intended function if properly used. If connectors are left in a partially mated, arc susceptible configuration or if the connector work loose during transit, arcing could cause injury and/or damage for a 42 volt electrical system.
An electrical connector assembly comprising a receptacle connector and a mating plug connector shiftable toward each other through a mating travel distance to fully mate the receptacle connector to the plug connector. The receptacle connector includes a plurality of receptacle terminals mounted in a receptacle housing and the plug connector including a plurality of plug terminals mounted in a plug housing. When mating begins between the receptacle connector and the plug connector, a first inertial spring force opposing mating is generated before receptacle terminals and plug terminals reach an intermediate, partially mated position where arcing is possible between the receptacle terminals and plug terminals. Upon further movement toward a fully mated position of the receptacle connector and plug connector, a second spring force acting in a mating direction is generated. The first and second spring forces act to urge the receptacle connector and the plug connector away from an intermediate, partially mated position where arcing is possible between the receptacle terminals and the plug terminals. The first and second mating forces together act over only a portion of the mating travel distance of the receptacle.
In one embodiment, the receptacle connector has an inertial protrusion extending into the mating cavity from at least one interior surface of a receptacle housing wall. An inertial protrusion is located on an exterior surface of the plug connector housing, and the receptacle connector inertial protrusion and the plug connector inertial protrusion are mutually engagable during mating and unmating to force mating terminals away from an intermediate, partially mated position in which arcing between receptacle connector terminals and plug connector terminals can occur. These inertial protrusions will increase the mating and unmating velocities to minimize the arc times. If contacts are to be mated and unmated under load, the contact disconnect time must be short and the mating velocities high.
In another embodiment, an over-center lever is mounted on one connector housing. The lever engages the mating electrical connector to apply a force along a mating axis to mate and unmate the two electrical connectors. An additional spring force parallel to the mating axis is generated by actuation of the lever. The spring force urges the mating electrical connector toward either a pre-stage position or a fully mating position and away from an intermediate partially mated position in which arcing may occur between pin terminals in the electrical connector and mating terminals in a mating electrical connector. This additional spring force is generated by deformation of a cantilever beam about which the over-center lever pivots.